Ataxia-telangiectasia (A-T) is a rare autosomal recessive disorder that affects approximately 1 in 40,000 to 1 in 100,000 live births. A-T is characterized by progressive cerebellar ataxia, telangiectasia, immunodeficiency, chromosomal instability, radiation sensitivity and increased incidence of lymphoid malignancies. Symptoms of A-T usually manifest in the first few years of life when children exhibit wobbly gait. Loss of neuromuscular control is relentless and, by their teens, children are usually confined to a wheel chair. A-T patients usually succumb to infection and/or lymphoma in the second decade of life. In addition, it has been estimated that up to 1% of the general population carries mutations in one allele of the ATM (ataxia-telangiectasia mutated) gene and ATM heterozygotes have an increased risk of developing breast cancer. The ATM gene encodes a large (369 kDa) protein, ATM, that is a member of the phosphatidyl inositol 3 kinase family of serine threonine protein kinases (the PIKKs). Cells that lack ATM are highly sensitive to ionizing radiation (IR) and are defective in the activation of multiple cell cycle checkpoints in response to IR and other DNA damaging agents. Since the discovery of the gene in 1995, it has become apparent that ATM plays a critical role in regulating the cellular response to IR and other DNA damaging agents. Understanding the function of ATM is of considerable importance to understanding the etiology of the disease, the molecular basis for increased cancer predisposition in A-T patients and ATM heterozygotes, and the molecular mechanisms that control how cells respond to radiotherapy and many chemotherapeutic drugs. In this application, funds are requested for partial support towards the 12th International Workshop on Ataxia-Telangiectasia and ATM, which will be held at the Banff Centre, Banff, Alberta, Canada, September 8th to 12th 2006. Objectives of the meeting: The objectives of the meeting are to bring together basic and clinical researchers working on various aspects of the clinical features of A-T, the role of ATM in the DNA damage response, and the role of ATM in the nervous system, in an informal but stimulating scientific atmosphere which will promote scientific interactions, discussions and research collaborations into understanding the functions of ATM and the biological basis of A-T. Our goal is to stimulate research that will lead to better understanding of and treatments for A-T. Specific areas of focus of the meeting will include the role of ATM and related proteins in the DNA damage response, the importance of chromatin in the activation of ATM, the role of ATM in the nervous system, mechanisms of neurodegeneration, the role of other DNA damage proteins in neuropathies, animal models of A-T, ATM in breast and other human cancers, epidemiology of ATM mutations, towards the development of new treatments for A-T, and an update on clinical trials for A-T. [unreadable] [unreadable] [unreadable]